The present invention relates to an optical network node with add-drop and/or cross-connect functions. Due to the increasing volume of data in optical networks, existing network capacity must be utilized optimally. At present, known add-drop multiplexers are not able to satisfy these increased demands on the network since they often only can be used statically. To provide optimal utilization of the network capacity, therefore, new and more comprehensive concepts for optimizing the traffic routing are necessary.
A further disadvantage of known optical add-drop multiplexers is that the network cannot be optimally occupied with transmit wavelengths. If, in the WDM network, wavelengths are occupied which should be fed in via an optical add-drop multiplexer, the tributary input of the optical add-drop multiplexer is blocked. It is not possible to feed a transmit wavelength into the optical WDM network.
Wavelength conversion in WDM networks previously only has been possible via an additional element; namely, with the aid of a transponder. This represents additional hardware expenditure and can lead to a further deterioration in the signal.
An additional disadvantage in previous optical add-drop multiplexers is that the tributary inputs only can be interconnected at the electrical level. Interconnection of the tributary inputs which is based on a uniform optical concept is not known.
It is, therefore, an object of the present invention to provide an optical network node with add-drop and/or cross-connect functions which enables wavelengths received, or to be transmitted, to be configured completely and freely.